Small Nucleolar RNAs: Insight Into Their Function in Cancer

Abstract

Small nucleolar RNAs (SnoRNAs) are a class of non-coding RNAs divided into two classes: C/D box snoRNAs and H/ACA box snoRNAs. The canonical function of C/D box and H/ACA box snoRNAs are 2'-O-ribose methylation and pseudouridylation of ribosomal RNAs (rRNAs), respectively. Emerging evidence has demonstrated that snoRNAs are involved in various physiological and pathological cellular processes. Mutations and aberrant expression of snoRNAs have been reported in cell transformation, tumorigenesis, and metastasis, indicating that snoRNAs may serve as biomarkers and/or therapeutic targets of cancer. Hence, further study of the functions and underlying mechanism of snoRNAs is valuable. In this review, we summarize the biogenesis and functions of snoRNAs, as well as the association of snoRNAs in different types of cancers and their potential roles in cancer diagnosis and therapy.

Keywords: biomarker; cancer; mRNA splicing; rRNA processing; sdRNA; small nucleolar RNA; therapy.

Figure 1

Structural features of C/D box and H/ACA box snoRNAs. (A) C/D box. snoRNAs contain two conserved sequence elements, named box C (RUGAUGA), and box D (CUGA). Box C and box D are close to each other by the base pairing of the 5′ and 3′ termini and fold into a k-turn motif. The antisense elements, upstream of the box D/D′ motifs, are complementary to target RNAs and catalyze site-specific 2'-O-methylation (2′-O-Me) of the NT in target RNAs. (B) H/ACA box snoRNAs contain evolutionarily conserved structural elements, including box H (ANANNA), box ACA motif, and two pseudouridylation pockets. Pseudouridylation pockets are complementary to the substrate RNAs and responsible for pseudouridylation (NΨ). Red line, target RNAs.